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The Linux kernel memory allocators from an exploitation perspective

In anticipation of Dan Rosenberg’s talk on exploiting the Linux kernel’s SLOB memory allocator at the Infiltrate security conference and because I recently had a discussion with some friends about the different kernel memory allocators in Linux, I decided to write this quick introduction. I will present some of the allocators’ characteristics and also provide references to public work on exploitation techniques.

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Black Hat Europe 2011 update

Black Hat Europe 2011 is now over and we are very happy to have participated once again in the best European IT security conference!

Continuing from our last year’s presentation, our talk this year focused on operating system kernel protections. Specifically, our researchers Patroklos Argyroudis and Dimitris Glynos collected their experiences from kernel exploit development and presented the ways in which modern operating systems protect their kernels from memory corruption attacks.

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FreeBSD kernel NFS client local vulnerabilities

census ID:census-2010-0001
CVE ID:CVE-2010-2020
Affected Products:FreeBSD 8.0-RELEASE, 7.3-RELEASE, 7.2-RELEASE
Class:Improper Input Validation (CWE-20)
Remote:No
Discovered by:Patroklos Argyroudis

We have discovered two improper input validation vulnerabilities in the FreeBSD kernel’s NFS client-side implementation (FreeBSD 8.0-RELEASE, 7.3-RELEASE and 7.2-RELEASE) that allow local unprivileged users to escalate their privileges, or to crash the system by performing a denial of service attack.

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FreeBSD kernel exploitation mitigations

In my recent Black Hat Europe 2010 talk I gave an overview of the kernel exploitation prevention mechanisms that exist on FreeBSD. A few people at the conference have subsequently asked me to elaborate on the subject. In this post I will collect all the information from my talk and the various discussions I had in the Black Hat conference hallways.

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Linux kernel SUNRPC off-by-two buffer overflow

census ID:census-2009-0005
Affected Products:Linux kernel versions from 2.6.32 to 2.6.32-rc7.
Class:Off-by-two stack buffer overflow.
Discovered by:Patroklos Argyroudis

We have found an off-by-two stack buffer overflow in the Linux kernel SUNRPC implementation. Linux kernel versions from 2.6.32 to 2.6.32-rc7 are affected.

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CVE-2008-3531: FreeBSD kernel stack overflow exploit development

About four months ago I developed a reliable exploit for vulnerability CVE-2008-3531, which is also addressed in the advisory FreeBSD-SA-08:08.nmount. In this post I will use this vulnerability to provide an overview of the development process for FreeBSD kernel stack exploits.

CVE-2008-3531 is a kernel stack overflow vulnerability that affects FreeBSD versions 7.0-RELEASE and 7.0-STABLE, but not 7.1-RELEASE nor 7.1-STABLE as the CVE entry seems to suggest.

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FreeBSD kernel stack overflows

Last May (2008/05/30) I presented my research on FreeBSD kernel stack overflows at the University of Piraeus Software Libre Society, Event #16: Computer Security. The slides from the talk are now available in our research section.

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FreeBSD kernel debugging

The FreeBSD kernel can be debugged with the ddb(4) interactive kernel debugger. Although the latest production release of FreeBSD (7.1 at the time of this writing) adds some very useful features, ddb is still lacking the flexibility of gdb.

The FreeBSD developer’s handbook has a section on kernel debugging using remote gdb, but it is not directly applicable to VMware-based installations. The solution is to use VMware’s feature of creating virtual serial ports as named pipes to emulate a serial connection between two FreeBSD virtual machines.

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